Battery monitor systems (BMS) include a housing for electrical and/or electronic components. Laser welding may be used to attach a cover to the BMS housing. Laser welding is expensive. Due to changes in environmental conditions (pressure, temperature, humidity) during product life, it is necessary to have a means to enable air equalization between the product external ambient and the ambient internal to the housing. Otherwise this might lead to damage in the electronic components inside. This is normally done letting a small gap or slot without welding between the housing and the cover.
But such a gap or slot without welding might allow water ingress and further protection means have to be added, for example forming an external wall in the cover (see, e.g., the prior art housing of FIGS. 10a and 10b). However this does not adequately prevent water ingress to the housing due to capillarity that results. As well, to enable the typical laser used in such laser welding to pass through the cover and reach the housing in order to attach the cover to the housing, the cover must be white in color, thereby requiring a paper label for the housing (instead of direct laser marking on it).
Thus, there exists a need for a housing for a BMS or other systems having an air chamber formed between the housing walls and the cover. Such a housing with an air chamber would reduce water ingress to the housing by minimizing the capillarity effect. Such a housing would also enable the use of friction surface welding (FSW) rather than laser welding to attach the cover to the housing, thereby reducing costs. Such FSW would also permit the use of a black or dark colored housing, thereby eliminating the need for a paper label as the housing may be labeled by laser marking.